Many Superfund site metal contaminants induce inflammation and oxidative stress in susceptible animal species and in humans. Chronic inflammation is a risk factor for a number of diseases. Some of those inflammatory responses are induced also in target cells and contribute to cell transformation, but it is not certain which of the induced factors are necessary for the transformation process to occur. Knowing that would allow for post-exposure targeted amelioration of the detrimental health effects. We propose to test the hypothesis that inflammatory cytokines and nitric oxide, as well as the resulting oxidative stress are necessary for cell transformation, and that anti-inflammatory, anti-oxidant inhibit the transformation process. We choose nickel and arsenic, two seemingly different metals, to test this hypothesis, because both contribute to oxidative stress and they share immunosuppressive properties. Using an immortal but non-tumorigenic human osteoblast-like cell line (HOS), we will establish whether: (a) Ni3S2 and NaAsO2 up regulate inflammatory cytokines IL-1, IL-1, and TNF-, and/or inducible nitric oxide synthase (iNOS), as well as markers of oxidative stress and of nitration, including transcription factors NF-B and AP-1, glutathione (GSH), 8-hydroxy-2'- deoxy guanosine (8-OHdG), and 3-nitrotyrosine; (b) they are necessary for anchorage-independent growth, as a measure of cell transformation, using specific anti-cytokine antibodies and iNOS inhibitors; and (c) anti- inflammatory antioxidant agents [N-acetyl-cysteine (NAC) caffeic acid phenethyl ester (CAPE), aspirin and Tamoxifen (TAM)] can inhibit Ni- and As-mediated cell transformation and responsible inflammatory factors. The second goal is to assess whether human lymphocytes of healthy people show inter-individual differences in their responses to Ni and As in regard to up-regulation of the factors found responsible for cell transformation in HOS cells, and whether the most active and least toxic among NAC, CAPE, aspirin, and TAM suppress these metal-induced cell transforming responses. Thus, this study should identify inflammatory factors needed for malignant cell transformation, means to suppress it after metal exposure, and factors that can provide a useful measure of inter-individual differences in responses to metal toxicants, which may be applicable in future screening of people exposed to Superfund sites.